Computed radiography (CR) is a reusable digital radiography modality. It utilizes reusable imaging plates incorporating a relatively thin, flexible construction. These imaging plates include a photostimulable phosphor layer, which converts radiation into a latent image. This image is retrieved using a laser-catalyzed photoemission phosphor layer. A CR scan produces a digital image. The imaging plate is erased with light to remove any remaining latent image that was not retrieved by the laser, thereby allowing the imaging plate to be reused. From a technician's standpoint, there is little difference between film and CR radiography, and general handling and use precautions are very similar, the biggest differences being related to the operation of the CR scanner, as opposed to the film processor.
Much of the advancement of radiographic technologies comes from the medical sector. Industrial non-destructive testing (NDT) markets are significantly smaller. The medical sector primarily uses energies of in the range of about 25-150 KeV for imaging. Advancements in the medical sector's technologies, equipment, and protocols emphasize lowering the radiation received by a patient undergoing a given test.
Most conventional imaging plates are constructed in a similar manner, and the following is not an exhaustive list of construction options, but covers the basic construction and functionality of the major layers. Starting from the back of the imaging plate and moving to the front (i.e., source side), the imaging plate includes:                A backing layer that provides structural support. This backing layer is relatively thick and made of plastic or the like.        A group of layers designed to reflect some wavelengths of light, but not others; in most plate constructions, the light emitted by the phosphor layer is reflected to decrease dose to the patient with only an acceptable sacrifice of resolution. Imaging plates designed for higher resolutions can be specifically designed to not reflect light emitted by the phosphor layer. Most imaging plates can be designed to not reflect light from the laser used to stimulate the phosphor layers.        The phosphor layer that reacts with x-rays to produce a latent image. The phosphor layer releases light in proportion to the radiation absorbed when stimulated by a laser.        A clear plastic protective layer used to protect the phosphor layer yet allow light to enter and leave the imaging plate. This layer is normally thinner on higher resolution plates.        Binding layers may also be present between other layers.The imaging plates are built by or for film manufacturers and have a very similar construction to film. However, film does not have the reflective/antireflective layers, and film replaces the phosphor layer with a layer of light and x-ray sensitive silver salts.        
Commercially available CR imaging plates are optimized for use in the KeV energy range. The typical setup for CR is as follows.                The imaging plate is placed inside a light-tight container, typically a film/CR cassette or sleeve, where the test object itself can serve as the light-tight container, or the x-ray area can be darkened.        Between the object and the source, a collimator(s) can be used to lessen the effect of scatter by decreasing the size of the primary beam.        At the source, some filtration can be used to preferentially remove lower energy radiation from the primary beam, decreasing scatter and effectively increasing the average energy of the primary x-ray beam.        
In medical radiography, great care is taken to minimize patient radiation exposure, and reduced radiation exposure is one focus of the present disclosure.
U.S. Pat. No. 4,712,011 is related to the present disclosure: An X-ray image intensifier tube which includes a luminescent layer with an absorption material having a high absorption for secondary X-rays which are generated in the original luminescent material and which are intercepted to only a very small extent by the original luminescent material. The absorption material may be included in the layer of luminescent material in homogeneous form as well as in recesses in said layer. In addition to improved resolution, a higher efficiency can be achieved by ensuring that, upon interception of the secondary radiation, the absorption material generates luminescent or secondary radiation which is intercepted by the original luminescent material.
U.S. Patent Application Publication No. 2010/0034351 is also related to the present disclosure: Disclosed are a radiation image conversion panel, which provides high luminance, an image without white or black defects, an image free from cracks and an image with reduced unevenness, and its manufacturing method. Also disclosed is an X-ray radiographic system employing the radiation image conversion panel. The radiation image conversion panel of the invention comprises a substrate and provided thereon, a reflection layer, a phosphor layer and a protective layer in that order, wherein the phosphor layer is composed of a phosphor crystal in the form of a column, and the reflection layer is formed by vapor phase deposition of two or more kinds of metals.